
public class Test {
    public static void main(String[] args) {
        Mystack mystack= new Mystack();
        mystack.push(10);
        mystack.push(20);
        mystack.push(30);
        System.out.println(mystack.pop());
        System.out.println(mystack.peek());
        System.out.println(mystack.size());

    }
}
